Wow, there is some serious misinformation in THAT thread.... geez.
Automated Sync is a good company, and we use them a lot. I sit on the 508 committee here at my company, and produce the 508 compliant media for us. Every video we do must be 508 compliant.
Vegas cannot, under any circumstance, created a closed captioned video. Doing open caption video can be done, but only manually. Doing subtitles can be done in am automated fashion in DVDA but only manually in Vegas.
Vegas is NOT the solution if you need to really do 508 compliant work.
If you need REAL closed caption support, Avid does it, and I believe FCP does as well. If you need subtitle support for the web, then using Vegas and a subtitle program like the excellent subtitle workshop (free) is your answer. I do most of our online captioning this way.